Octane improvement of gasoline with porous solids

In this work is performed the study of the hexane isomers separation with MOFs in order to improve the octane number of gasoline. The studies were performed with MOFs: MIL-125-Amine, MIL-53(Fe)-Cl, MIL-53(Fe)-Br and Fe-TazBz(DMF). It was observed that higher loadings were obtained for high pressure and low temperature. With MOFs like MIL-53(Fe)-Cl and MIL-53(Fe)-Br the components weren’t separated. In MIL-125-Amine hexane isomers were separated according to their boiling point, but the selectivity was small. The best result was obtained with MOF Fe-TazBz(DMF), because of the higher affinity of n-hex with this MOF, the separation from the other isomers was easier.Neste trabalho, mostra-se a capacidade de separação de isómeros do hexano com MOFs para aumentar o índice de octano da gasolina. O estudos fizeram-se nos MOFs: MIL-125-Amine, MIL-53(Fe)-Cl, MIL-53(Fe)-Br and Fe-TazBz(DMF). Observou-se que as maiores capacidades obtêm-se para a temperatura baixa e pressão alta. Nos MOFs MIL-53(Fe)-Cl e MIL-53(Fe)-Br os componentes não foram separados. No MOF MIL-125-Amine os isómeros foram separados seguindo aponto normal de ebulição dos compostos mas a selectividade é baixa. O melhor resultado obteve-se para o MOF Fe-TazBz(DMF) devido à maior afinidade deste composto com o MOF separando-o dos outros isómeros

Water activity and freezing points in aqueous solutions of manganese nitrate: experimental and modeling

The water activities of manganese nitrate solutions were measured using a humidity sensor instrument up to almost the saturation molality at 298.15 K; the thermodynamic properties of the system were described by the Pitzer model and specific interaction theory (SIT). The evaluation of the ion interaction parameters for the Pitzer model and SIT were carried out using experimental freezing points and osmotic coefficients of manganese nitrate aqueous solutions, collected from the open literature, and the water activity data measured in this work. A set of Pitzer and SIT parameters were estimated using a temperature dependency, that enables us to cover wider temperature ranges, and consequently calculate system properties to higher molalities. Both approaches represent very satisfactorily, and with similar accuracy, the experimental data and the calculated manganese nitrate molal activity coefficients are comparable to those already published for analogous systems. Additionally, the Pitzer model was also able to calculate the ice curve and the solubility branch of manganese nitrate hexahydrate up to a salt solution 6.5 mol-kg-1.This work was developed in the scope of the projects POCI-01-0145-FEDER- 006984—Associate Laboratory LSRE-LCM both funded by European Regional Development Fund (ERDF) through COMPETE2020—Programa Operacional Competitividade e Internacionalização (POCI)—and by national funds through FCT—Fundação para a Ciência e a Tecnologia. This work is also a result of project ‘‘AIProcMat@N2020—Advanced Industrial Processes and Materials for a Sustainable Northern Region of Portugal 2020’’, with the reference NORTE-01-0145-FEDER-000006, supported by Norte Portugal Regional Operational Programme (NORTE 2020), under the Portugal 2020 Partnership Agreement, through ERDF.info:eu-repo/semantics/publishedVersio

Electrolyte effects on the Amino acid solubility in water: solubilities of Glycine, l-Leucine, l-Phenylalanine, and l-Aspartic acid in salt solutions of (Na+, K+, NH4+)/(Cl–, NO3–)

The solubilities of glycine, L-leucine, L-phenylalanine, and L-aspartic acid in aqueous solutions of the salts composed by combining Na+, K+, and NH4 + cations and Cl− and NO3 − anions were measured up to 2.0 salt molality at 298.2 K by the analytical gravimetric method. Using these data along with a review of literature information, encompassing all amino acids for which solubility is available in the studied aqueous electrolyte solutions, allowed us to interpret the effect of the functional groups of amino acids on their solubility. The four amino acids studied here showed higher solubility in aqueous solutions of salts with the nitrate anion. Except for L-aspartic acid with a polar side chain, amino acids with apolar side chains presented the highest salting-in effect in aqueous salt solutions with NH4 +. The cations Na+ and K+ did not seem to establish relevant interactions with the amino acids and had little impact on their aqueous solubility.This work was developed within the scope of the project CIMO-Mountain Research Center, UIDB/00690/2020 and CICECO-Aveiro Institute of Materials, UIDB/50011/2020 and UIDP/50011/2020, financed by national funds through the Portuguese Foundation for Science and Technology (FCT)/MCTES. Mehriban Aliyeva thanks FCT and European Social Fund (ESF) for her Ph.D. grant (SFRH/BD/139355/2018).info:eu-repo/semantics/publishedVersio

Salt effects on the solubility of aromatic and dicarboxylic amino acids in water

The salt effect on the solubility of the amino acids l-aspartic acid, l-glutamic acid, l-tryptophan, and l-tyrosine, seldomly found in the literature, was studied at 298.2 K, in aqueous solutions of KCl and (NH4)2SO4, for salt concentrations up to 2.0 mol·kg−1. In this concentration range, both salts are salting-in agents for glutamic acid and aspartic acid, with a stronger effect induced by (NH4)2SO4. Regarding the two aromatic amino acids, a slight increase in the solubility was obtained at low salt concentrations, followed by a stronger salting-out effect, more pronounced by (NH4)2SO4 than by KCl. The relative solubility data obtained in this work were compared to literature data for other amino acids in the same electrolyte solutions to establish a relative solubility ranking connected to their structure. Finally, the solubility data were modeled using the electrolyte Perturbed-Chain Statistical Association Theory (ePC-SAFT). The modeling requires parameters for the amino acids and ions as well as melting properties of the amino acids. All these parameters and properties were obtained from previous works. To quantitatively describe the solubility of amino acids upon salt addition, binary interaction parameters (kij) between any amino acid and anions were determined, while between any amino acid and the cations were fixed to kij = 0.08. The kij parameters between amino acid and the inorganic anions show very similar values for amino acids of the same chemical class (e.g. kij between anion and amino acid with apolar side chains), which may be used to systematically reduce the number of adjustable parameters in future work.publishe

Electrolyte effects on the amino acid solubility in water: solubilities of glycine, l-leucine, l-phenylalanine, and l-aspartic acid in salt solutions of (Na+, K+, NH4+)/(Cl–, NO3–).

The solubilities of glycine, L-leucine, L-phenylalanine, and L-aspartic acid in aqueous solutions of the salts composed by combining Na+, K+, and NH4 + cations and Cl− and NO3 − anions were measured up to 2.0 salt molality at 298.2 K by the analytical gravimetric method. Using these data along with a review of literature information, encompassing all amino acids for which solubility is available in the studied aqueous electrolyte solutions, allowed us to interpret the effect of the functional groups of amino acids on their solubility. The four amino acids studied here showed higher solubility in aqueous solutions of salts with the nitrate anion. Except for L-aspartic acid with a polar side chain, amino acids with apolar side chains presented the highest salting-in effect in aqueous salt solutions with NH4 +. The cations Na+ and K+ did not seem to establish relevant interactions with the amino acids and had little impact on their aqueous solubility.This work was developed within the scope of the project CIMO-Mountain Research Center, UIDB/00690/2020 and CICECO-Aveiro Institute of Materials, UIDB/50011/ 2020 and UIDP/50011/2020, financed by national funds through the Portuguese Foundation for Science and Technology (FCT)/MCTES. Mehriban Aliyeva thanks FCT and European Social Fund (ESF) for her Ph.D. grant (SFRH/BD/139355/2018).info:eu-repo/semantics/publishedVersio

Computer code: Response of permafrost extent and carbon content to increasing global mean surface temperature

We used this software to reproduce the approach of Chadburn et al. (2017) to assess the response of circum-Arctic equilibrium permafrost extent to an increase in global mean surface temperatures (GMST) compared to pre-industrial levels. In deviation from the work of Chadburn et al., we used ERA5-Land data as a climatological baseline. In addition, we combined the approach with the soil organic carbon data by Hugelius et al. (2014) to quantify the equilibrium permafrost carbon content in response to GMST increase. The Python script calculate_responses.py takes the ERA5 and NCSCDv2 input data from the ./input/ directory, calculates the respective responses and saves them into the ./output/ directory. The Python script plotting_article.py has been used to create figures for a related scientific article which are saved in the ./plots/ directory. References Chadburn, S. E., Burke, E. J., Cox, P. M., Friedlingstein, P., Hugelius, G., & Westermann, S. (2017). An observation-based constraint on permafrost loss as a function of global warming. Nature Climate Change, 7(5), 340–344. https://doi.org/10.1038/nclimate3262 Hugelius, G., Strauss, J., Zubrzycki, S., Harden, J. W., Schuur, E. A. G., Ping, C.-L., Schirrmeister, L., Grosse, G., Michaelson, G. J., Koven, C. D., O’Donnell, J. A., Elberling, B., Mishra, U., Camill, P., Yu, Z., Palmtag, J., & Kuhry, P. (2014). Estimated stocks of circumpolar permafrost carbon with quantified uncertainty ranges and identified data gaps. Biogeosciences, 11(23), 6573–6593. https://doi.org/10.5194/bg-11-6573-201

Solubilities of amino acids in aqueous solutions of chloride or nitrate salts of divalent (Mg2+ or Ca2+) cations

The solubilities of glycine, L-leucine, L-phenylalanine, and L-aspartic acid were measured in aqueous MgCl2, Mg(NO3)2, CaCl2,, and Ca(NO3)2 solutions with concentrations ranging from 0 to 2 mol/kg at 298.2 K. The isothermal analytical method was used combined with the refractive index measurements for composition analysis guaranteeing good accuracy. All salts induced a salting-in effect with a higher magnitude for those containing the Ca2+ cation. The nitrate anions also showed stronger binding with the amino acids, thus increasing their relative solubility more than the chloride anions. In particular, calcium nitrate induces an increase in the amino acid solubility from 2.4 (glycine) to 4.6 fold (L-aspartic acid) compared to the corresponding value in water. Amino acid solubility data in aqueous MgCl2 and CaCl2 solutions collected from the open literature were combined with that from this work, allowing us to analyze the relations between the amino acid structure and the salting-in magnitude.This work was developed within the scope of the project CIMO-Mountain Research Center, UIDB/00690/2020 and LA/P/0007/2020 and CICECO-Aveiro Institute of Materials, UIDB/50011/2020 & UIDP/50011/2020 and LA/P/0006/2020, financed by national funds through the Portuguese Foundation for Science and Technology (FCT)/MCTES. Mehriban Alyieva thanks FCT and European Social Fund (ESF) for her Ph.D. grant (SFRH/BD/139355/2018).info:eu-repo/semantics/publishedVersio